Axial-flow steam turbine



Feb. 4, 1930. A. LYSHOLM AXIAL FLOW STEAM TURBINE Filed May 3, 1928Patented 4, 1930 v IU-hl I TED STATE-S PATENT OFFICE srnoms ANGTURBIN, FSTOCKHOLM SWEDEN ALF'LY SHOLM, OF STOCKHOLM, SWEDEN, ASSIGIfTOR TOAKTIEBOLAGET 'IJUNG- SWEDEN, A JOINT-STOCK COMPANY OF axmrrrnow STEAMTURBINE Application filed May 3, 1928, Serial No. 274,907, and in SwedenMay 11, 1927.

Heretofore, turbines have been so constructed that an outer capsurroundsan inner guide-blade-carrying cap, and that the space betweenthese caps constitutes the outlet of the turbines, or is in connectionwith such outlet. 7

In such constructions, the inner cap and the outer cap have been madeintegral, but in such tial joints, it has a manner that the said unitedcaps would be axially divided into two halves surrounding the innerrotating parts of the turbine, which halves have been held together bymeans of bolts. If the driving medium is admitted to such a turbine, thepressure acting within the turbine tends to force the connecting flangesapart and cause a leak. To obviate this and cause the steam pressure tobring about automatic ti htening of the axial parbeen previously proosed to conduct the driving medium throng the turbine in such a mannerthat steam of high pressure would enter the space between the mner andthe outer cap, which caps are con- 7 structed as separate parts, Inorder to avoid leaky joints the outer up has been part1 constructed soas 'to be axially undivide Such constructions, however, are not suitablein turbines operating with a back pressure and under very highpressures, for mstance 1150 at., since the exhaust steam will in this 1case still have a very high pressure, for instance 75 at. Even steam ofthis, pressure will force the connecting flanges apart and cause openjoints, if such steam is conducted through axially divided casings, capsor steam conduits.

The present invention refers to turbines of b drawing showing an axialcross section through a turbine according to the invention.

In the drawing, 1 designates the shaft of the turbine, which shaft isformed at its one end into a pinion 2 and at its other end into anattaching device 3 for the turbine rotor 4. The shaft 1 terminates in aninner hollow Epace and an outer conical portion, as at 3,

tting to a correspondingly shaped portion of the turbine rotor 4. Incertain places between the conical surfaces, conical pins 5 are forcedinto correspondin holes, which pins are retained by means 0 the centralbolt 6. The turbine rotor 4 is formed into or connected with turbinedisks 7, 8, 9 and 10 adapted to carr blades 11, 12, 13 and 14. Fittedbetween t ese turbine disks are guideblade-carrying rings 15, 16 and 17,which are shaped in connection with or united with an inner ca 18. Thiscap 18 is axiall divided in the 'p ane of the paper, as are t eguideblade-carrying rings 15, 16 and 17. The two halves of the cap 18are ke t together by means ofi bolts, as at 19, 20 an 21. Between theturbine rotor 4, or the parts connected therewith, and the inner cap 18,or the parts connected therewith, packings have been provided inknownmanner by means of thin wearing edges, as will appear from the drawing.I

The inner' divided turbine cap 18 is attached to a ring 23 by means ofbo ts 22. This ring 23 is secured, in turn by means of bolts '24, to anundivided outer cap 25 surroundin the whole turbine, said cap 25 beingsecure a ring 28 fixedly connected therewith, in such a manner thatfacilities are provided for the expansions of said cap by reason oftensions caused by heat. During the expansion of the turbine .cap, thesame will slide on the studbolts 26 so as to reduce the play 29 betweenthe cap 25 and the ring 28. In this case, too, the frame 27 constitutesa casing surrounding the toothed gearing with which the pinion2cooperates, and also carries one of the bearings 30 of the turbineshaft.

The supply conduit 31 for the driving medium is arranged in conjunctionwith the y means of stud-bolts 26 to a frame 27 or to 'ring 23. Theseparts form together the head piece of the turbine. The supply conduit 31is formed with a flange 32, and is attached to the ring 23 by means ofbolts provided between the bolts 22. Thus the supply conduit 31 of theturbine is arranged centrally about the geometrical axis of the turbine,and does not cause any oblique forces detrimental to the turbine.

The driving medium or steam passes through the supply conduit. 31 andthrough the openings or nozzles 33, whereupon said driving medium orsteam flows through the blades 11, 12, 13 and 14 of the turbine andthrough the guide blades provided therebetween, while delivering energy.The turbine described is intended to operate at an initial pressure of150 kilograms per square centimeter and at a speed of rotation of 12000revolutions per minute. Of this pressure, the turbine will transfer intokinetic energy a fall of pressure of about 7 5 kilograms per squarecentimeter, for which reason an approximate pressure of 75 kilograms persquare centimeter will prevail, during the running of the turbine, inthe space 34 between the outer cap 25 and the inner cap 18, whereas theaverage steam pressure within the inner cap 18 will be about 115kilograms per square centimeter. Inasmuch as the difference in pressurebetween the space inside ,the inner cap 18 and the space 34 between thecaps is smaller than the diflerence in pressure between the space 34 andthe space surrounding the outer cap, the strains Willbe greater on theouter cap than on the inner one: Thus the advantage is obtainedaccording'tothe invention, in regard to a steam-tight fit, that steam oflower pressure is conducted between theinner divided and'the outeraxially undivided eap surrounded by atmospheric pressure, whereas steamof a higher pressure is conducted through the. inner axially divided capsurrounded by exhaust steam. If the pressure, within theturbine, of thedriving medium would then force axial connecting flanges apart and causethem to become untight, this will have no influence but that smallquantities of steam will leak out into the space between the caps. Theloss produced 'hereby will have a minimum value when the steam presentin this space is then used for other useful purposes. l

The steam entering the turbine through the nozzles 33 will obviouslyfill the space in front of the turbine disk 7 and bring about an axialpressure, counted in the direction of flow of the steam. To counteractthis pressure, a balancing plunger 37 is arranged, whichis'fixedlyarranged on the turbine rotor 4 and provided in known manner withtightening members 38 directed toward stationary members in the steaminlet 31. Moreover, the turbine is provided, in addition to the plunger37 with the tightening members 38 the'inner cap.

pertaining thereto, with connecting channels 42 between the space 39 andthe space 41 after the last turbine disk 10. Thus the pressure in thespace 39 will be approximately equal to the pressure in the outlet ofthe turbine, by reasonof which an axial pressure will also be producedin a direction opposed to that of the pressure on the balancing plunger37 These pressures will be approximately equal, first, because thediflerence, in steam pressure on both sides of the balancing plunger 37is approximately equal to the difference in steam pressure in front ofthe turbine disk 7 and behind the turbine disk 10, and, second, becausethe'pressure surface of the balancing plunger 37 is approximately equalto the pressure surface of the turbine disk 7. y

The turbine is provided in known manner with packing means at 40 inconnection with means to suck out leaking steam.

According to the invention, the ring 23 and the steam supply part 31 areformed into a head wall without axial connecting flanges, said head wallcovering so large an opening that the inner cap 18 may be taken outtherethrough together with the rotating parts pertaining to the turbine,the cap 18 being formed at 35, into an enlarged flange or the likehearing on a corresponding flange or the like in the outer cap 25. Bythis means the inner cap 18 is guided while the opening will at the sametime become so large that the inner parts may be conveniently removedout of and introduced into the outer cap. If the steam supply conduit 31isremoved and the a ring 23 is made free both from the inner and theoutercaps, the cap 18 as well as the rotor 4 may, after the central bolt6 has been reinoved and the pins 5 have been released, be removedaxially through the opening limited byfthe enlarged portion at 35 on theouter cap 25. a i

What I claim is 1. In combination in a turbine, an axially divided innercap carrying guide blades, an axially undivided outer cap surroundingsaid inner cap, said outer cap being adapted to limit the outlet of theturbine outwardly and being under a lower pressure than the inner cap.

steam supply member,'an axially divided inner cap, an axially undividedouter cap surrounding said inner cap, a frame connected with said outercap, said outer cap carrying said inner cap as well as the steam supply2. Incombination in a turbine having amember of the turbine, and aconduit connecting the low pressure part of the turbine with the spacebetween said caps, whereby said outer cap is under a lower pressure than3, In combination in a turbine, an axially dlvided mner cap, an axiallyundivided outer cap surrounding said inner cap, a frame conspace betweenthe two casings, said undivided nected with said outer cap, carryingsaid inner cap, an tainmg the steam supply member of the turbine, saidouter cap carrying said end plate and said end plate covering an openingfor inserting and removing said inner cap and the moving arts of theturbine.

4. In com ination in a turbine, an axially divided inner cap, said innercap carrying guide blades, an axially undivided outer cap surroundingsaid inner cap, a frame connected with said outer cap, said outer capcarrying said inner ca an end plate containlng the steam supp y memberof the turbine, said outer cap carrying said end plate and said endplate covering an opening for inserting and removing said inner cap andthe moving arts of the turbine.

5. In com ination in a turbine, an axially divided inner cap, said innerca carrying guide blades, an axially undivide outer cap surrounding saidinner cap, a frame expansibly connected with said outer cap, said outercap carryin said inner cap, an end late containing t e steam supplymember 0 the turbine, said outer cap carrying said end containing t esteamsupply member 0 the] turbine, said outer cap carrying said endplate and said end platecovermg an opening for inser'tin and removingsaid inner cap and the movlng parts of the turbine.

6. In combination in-a turbine, an axially divided inner cap, said innerca carrying guide blades, an axially undivide outer cap surrounding saidinner cap, a frame expansibly connected with said outer cap, said outer7 cap carryin I said inner cap, an end late plate, said end platecovering an opening-for inserting and removing sai inner cap'and themoving parts of the turbine and a con! duit connecting the low pressurepart of-the' turbine with the space between said caps in order to keepsaid outer cap under a lower pressure than the inner cap.

7 In combination in a turbine, an axially divided innercap carryingguide blades, an axially undivided outer cap surrounding said inner capand adapted to limit the outlet of the turbine outwardly, a conduitconnecting the low pressure part of said turbine with the space betweensaid caps, the fall of pressure in the turbine being such that thedifference between the pressure prevailing within thev inner cap and thepressure in said space will be smaller than the difference between thepressure in said space and the atmospheric pressure.

8. In a turbine, an axially divided casing, an inlet member forsupplying high pressure elastic fluid to said divided casing, anundivided casing surrounding said divided casing leaving a space betweenthe two casings, an exhaust member in communication with said ALF L saidouter cap casing constructed to withstand a portion of end plate con'--said high pressure elastic fluid.

In testimony whereof I aflix llYlysfi ature. LM.

